Recent silicon-based semiconductor devices increasingly have more improved performance due to their miniaturized design rules. A substrate used for these devices mainly includes a SOI (Silicon on Insulator) substrate. This SOI substrate enables small junction capacitance and suppression of leak current of a semiconductor device, and has good high-frequency characteristics, and so is suitable for the applications of power devices and high-frequency devices.
A SOI substrate is typically manufactured by a SIMOX (Separation by IMplantation of OXygen) method or a bonding method. The SIMOX method is to implant oxygen ions at high concentration in a silicon substrate as semiconductor, followed by heat treatment at high temperatures, so as to form an oxide film as an insulator in the substrate to be a SOI substrate. The bonding method is to bond a silicon substrate as semiconductor and a support substrate as insulator, followed by thinning of the silicon substrate to form a SOI substrate. A support substrate of the SOI substrate typically is an insulating substrate only. For some applications, however, a substrate made of semiconductor or insulator at least having an insulating layer at the surface part including a silicon layer of the support substrate also can be used. In this case, the insulating layer and the insulating substrate may be made of the same material or different materials.
The SOI substrate is used for a transferring substrate as well. The transferring substrate is used for manufacturing of a backside illumination-type CMOS (Complementary Metal Oxide Semiconductor) sensor (Patent document 1), a high-frequency semiconductor device (Patent document 2) and the like. The backside illumination-type CMOS can be manufactured as follows, for example. After a semiconductor device layer is formed in a silicon layer of a SOI substrate, the semiconductor device layer and a silicon substrate as another substrate for supporting are bonded. Then, the insulating substrate part or a part of the insulating substrate part and a part of the silicon layer of the SOI substrate, which are on the back side of the semiconductor device layer bonded to the silicon substrate, are removed by means such as back grinding, polishing, or etching so as to bring the silicon layer at the surface. Then, a color filter and an on-chip lens are formed on this silicon layer to form a backside illumination-type CMOS. The above-stated means such as back grinding used for removal of the insulating substrate part or a part of the insulating substrate part and a part of the silicon layer of the SOI substrate is means used for manufacturing of a backside illumination-type solid-state imaging devices. Similarly for high-frequency semiconductor devices, a SOI substrate is used for transferring a high-frequency semiconductor device layer into another support substrate.